Physical Geography
GEOGRAPHY 1710
Chapter 3
DAVID R. SALLEE
Earth’s Modern Atmosphere
Atmospheric Profile
z
z
z
Atmosphere
extends to 32,000
km (20,000mi)
from surface
Exosphere’
Exosphere’s top is
at 480 km (300
mi)
Three criteria to
examine
atmosphere
– Composition
– Temperature
– Function
Atmospheric Pressure
Figure 3.2
Atmospheric Composition
z Homosphere
atmosphere
– inner
– Surface to 80 km (50
mi)
– Gasses evenly blended
z Heterosphere
atmosphere
– outer
– 80 km (50 mi)
outwards
– Layers of gasses
sorted by gravity
Figure 3.3
1
Atmospheric Temperature
z Troposphere
– Surface to 18 km (11
mi)
– 90% mass of
atmosphere
– Normal lapse rate –
average cooling at
rate of 6.4°
6.4°C/km
(3.5°
(3.5°F/1000 ft)
Atmospheric Temperature
z Stratosphere
– 18 to 50 km (11 to
31 mi)
z Mesosphere
– 50 to 80 km (30 to
50 mi)
z Thermosphere
– Roughly same as
heterosphere
– 80 km (50 mi)
outwards
Atmospheric Function
z Ozonosphere
– Part of stratosphere
– Ozone (O3) absorbs UV
energy and converts it
to heat energy
z Ionosphere
– Absorbs cosmic rays,
gamma rays, XX-rays,
some UV rays
Variable Atmospheric
Components
z Natural
Sources
z Natural
Factors That
Affect Air
Pollution
z Anthropogenic
Pollution
2
Natural Factors That Affect
Air Pollution
Temperature Inversion
z Winds
z Local
and
regional
landscapes
z Temperature
inversioninversionSituation where a layer of warmer air exists above the
Earth's surface in a normal atmosphere where air
temperature decreases with altitude. In the warmer
layer of air, temperature increases with altitude.
Figure 3.9
Pollution Sources
Anthropogenic Pollution
(Caused by Humans)
z Carbon
monoxide
z Photochemical
smog
z Industrial
smog and
sulfur oxides
z Particulates
Photochemical
Smog
Figure 3.10
Photochemical smog
is a condition that
develops when
primary pollutants
(oxides of nitrogen
and volatile organic
compounds created
from fossil fuel
combustion) interact
under the influence
of sunlight to
produce a mixture of
hundreds of different
and hazardous
chemicals known as
secondary pollutants.
Figure 3.14
3